The invention is based on a contact zone for a power breaker, as claimed in the precharacterizing clause of claim 1.
Laid-open Specification DE 196 13 568 A1 discloses a power breaker which is filled with an insulating gas and may be used in an electrical high-voltage network. This power breaker has a cylindrical quenching chamber with a contact zone located in its rated current path. Two stationary consumable contacts, are provided in the contact zone, are arranged on a central axis and, when the power breaker is connected, are electrically conductively connected by means of a bridging contact. In this case, the bridging contact is arranged in the interior of the rotationally symmetrical consumable contacts. In order to prevent excessive radial movement of the arc bases, the mutually facing end surfaces of the consumable contacts are at least partially covered with insulation. The fitting of the insulating cover is comparatively complex, since this cover can be distorted under the influence of the temperatures that occur in the arcing zone.
The invention, as it is characterized in the independent claim, achieves the object of providing a contact zone for a power breaker, in which insulating covers for the end surfaces of the consumable contacts are designed with good dielectric characteristics, and are simple to install.
The advantages achieved by the invention are that the covers can always comply with the stringent dielectric requirements in this area, despite deformation caused by heat, in particular even during the disconnection process, and immediately after it.
This invention is based on the contact zone of a quenching chamber which is arranged rotationally symmetrically about a central axis and is filled with an insulating medium, having at least two stationary consumable contacts which are in the form of contact rings and which, when the quenching chamber is closed, are electrically conductively connected by means of a bridging contact which is arranged centrally and can move axially and having electrically insulating covers, which at least partially cover mutually facing end surfaces. Here, for the first time, an annular gap which annular gap is open in the radial direction, originates from a contact-making edge of the cover, is provided between a contact-making surface and an insulating cover, and has a wedge-shaped cross section, with the edge being dielectrically shielded by means of an annular bead which projects beyond the contact-making surface.
One particular advantage is that the edge is always pressed by spring force against the contact-making surface, thus ensuring that no erosion particles can penetrate into the annular gap, where they could have a dielectrically disadvantageous effect.